Optimisation of wind instruments revisited

Computer optimization of brass wind instruments has attracted attention during the last years. Nevertheless, there are some difficulties which still have to be overcome before this promising technique will be widely accepted. First, bore reconstruction from acoustical measurements works well for short and narrow geometries, but accurate bore profiles of whole instruments are still some kind of challenge. Second, physical modeling of real instruments with mouthpiece and bell radiation does not perfectly match corresponding measurements. This makes it difficult to achieve a good starting point for subsequent optimization. And third, currently available computer power still does not allow optimization of whole instruments with any method better than plane wave propagation. This paper proposes a solution to these issues, making bore reconstruction and optimization more useful for instrument makers. Having some prior knowledge about the bell geometry or performing a second measurement of the interior impedance which represents the whole bell and its radiation into the room, allows to eliminate the main sources of errors and reduces the numerical complexity to such a degree that modal decomposition methods become feasible in optimization. A bore reconstruction of a typical Bb-trumpet is presented and the possible matching between theory and experiment is shown.